The term surfactant is a coined contraction for “surface active agent”. It refers to a class of materials that are amphillic, that is possess groups within one molecule that would be insoluble in each other if mixed separately. Most commonly these two groups are water soluble (hydrophilic) and oil soluble (lipophilic).
Standard surfactants, also called fatty surfactants, are commonly made from oil soluble groups like fatty alcohols, which are made soluble by reaction with ethylene oxide. Ethylene oxide is a reactive epoxide belonging to a class of compounds called oxiranes. When ethylene oxide is reacted with a fatty alcohol a more water soluble ether group is formed.

Polyoxyalkylene based surfactants have been known for many years and make up a class of compounds referred to as non-ionic surfactants. Recently, surfactants based upon PEG have become less desirable by consumers based upon the fact they are not considered green.
There has been a push to develop surfactants based upon natural, renewable, inexpensive and available raw materials. One such material is glycerin. As biodisel becomes more and more common in our national quest to limit dependence upon petroleum, glycerin becomes more available and less expensive. This is because glycerin is a by-product of the process. The polyester compounds of the present invention unlike many of the synthetic detergents in use today are biodegradable.
Glycerin has been used in a variety of applications, including polyglycerin used as a base to make esters. Polyglycerin esters are used as oils and not as foaming surfactants. Typical of the preparation of esters of polyglycerin is U.S. Pat. No. 3,936,391 to Gabby issued in 1976 teaches a Polyglycerol ester composition classified as imitation butter, margarine, cheese spreads, dips, frozen desserts including ice cream and sherbert, puddings, icings, salad dressings, sauces, and the like. It clearly is an oil and noty a water soluble surfactant.
The problem with using glycerin as a raw material to make high foaming surfactants is that the derivatives heretofore attempted have lack the water solubility that can be achieved when using PEG based products. Put another way the glycerin is a far less effective material at making fatty materials water-soluble.
The present invention addresses this long felt need for a surfactant based upon glycerin. Critical to the functioning of the present invention is the preparation of a poly ester of glycerin and an anhydride, linking the groups together, but equally important is the inclusion of an alkenyl succinic anhydride into the polyester in the proper ratio in order to build in domains of oil soluble groups. We have surprisingly found that if incorporated into the polyester, products with low levels of domains derived from alkenyl succinic anhydride produce copious foam.
Alkenyl succinic anhydrides are known materials. Perhaps the most important patent is U.S. Pat. No. 5,319,030, incorporated herein by reference, to Harrison et al not only teaches a process for the preparation of an alkenyl-substituted succinic anhydride, but also provides a review of alternate methods to make and hydrogenate these materials. Alkenyl-substituted succinic anhydrides have been prepared by two different processes, a thermal process (see, e.g., U.S. Pat. No. 3,361,673) and a chlorination process (see e.g., U.S. Pat. No. 3,172,892). The polyisobutenyl succinic anhydride (“PIBSA”) produced by the thermal process has been characterized as a monomer containing a double bond in the product. Although the exact structure of chlorination PIBSA has not been definitively determined, the chlorination process PIBSA materials have been characterized as monomers containing either a double bond, a ring other than succinic anhydride ring and/or chlorine in the product. The analytical difficulties offered by analysis of both the succinic derivatives used as raw materials in the preparation of the compounds of the present invention and the complex oligomeric mixtures that result when the polymer is made makes the preferred method of claiming the polymers of the present invention product by process claims.
Polyesters of the present invention and their unique surfactant properties have been heretofore unknown in detergent sciences.